By ELENA BECATOROS and JON GAMBRELL
ZAPORIZHZHIA, Ukraine (AP) -- The United Nations raced Friday to rescue more civilians from the tunnels under a besieged steel plant in Mariupol and the city at large, even as fighters holed up at the sprawling complex made their last stand to prevent Moscow's complete takeover of the strategic port.
The fight for the last Ukrainian stronghold in a city reduced to ruins by the Russian onslaught appeared increasingly desperate amid growing speculation that President Vladimir Putin wants to finish the battle for Mariupol so he can present a triumph to the Russian people in time for Monday's Victory Day, the biggest patriotic holiday on the Russian calendar.
Some 2,000 Ukrainian fighters, by Russia's most recent estimate, are holed up in the vast maze of tunnels and bunkers beneath the Azovstal steelworks, and they have repeatedly refused to surrender. Ukraine has said a few hundred civilians were also trapped there, and fears for their safety have increased as the battle has grown fiercer in recent days.
"Our colleagues are currently on the ground," U.N. spokesman Stephane Dujarric said of the latest evacuation effort. "We are in an extremely delicate phase of this operation, working in close coordination with both the Ukrainian authorities and the Russian authorities.
He declined to share details "for the sake of the safety of those we're trying to get out, and, of course, for our own staff, which are there."
It could takes days to know whether the latest U.N. effort to evacuate civilians succeeded, since people escaping Mariupol typically have to pass through contested areas and many checkpoints before reaching relative safety in the Ukrainian-controlled city of Zaporizhzhia, about 140 miles (230 kilometers) to the northwest.
Some of the plant's evacuees spoke to the AP about the horrors of being surrounded by death in the moldy, underground bunker with little food and water, poor medical care and diminishing hope. Some said they felt guilty for leaving others behind.
"People literally rot like our jackets did," said 31-year-old Serhii Kuzmenko, who fled along with his wife, 8-year-old daughter and four others from their bunker, where 30 others were left behind. "They need our help badly. We need to get them out."
Fighters defending the plant said Friday on Telegram that Russian troops fired on an evacuation vehicle on the plant's grounds. They said the car was moving toward civilians when it was hit by shelling, and that one soldier was killed and six were wounded.
Moscow didn't immediately acknowledge renewed fighting there Friday.
Russia took control of Mariupol, aside from the steel plant, after bombarding it for two months. Ahead of Victory Day, which marks the Soviet Union's triumph over Nazi Germany, municipal workers and volunteers cleaned up what remains of the city, which had a prewar population of over 400,000 but where perhaps 100,000 civilians remain with little food, water, electricity or heat.
The fall of Mariupol would deprive Ukraine of a vital port, allow Russia to establish a land corridor to the Crimean Peninsula, which it seized from Ukraine in 2014, and free up troops to fight elsewhere in the Donbas, the eastern industrial region that the Kremlin says is now its chief objective.
Asked whether Russia would soon take full control of Mariupol, Ukrainian President Volodymyr Zelenskyy said: "Mariupol will never fall. I'm not talking about heroism or anything."
"It is already devastated," he told a meeting at London's Chatham House think tank. He also said he remains open to negotiations with Russia, but repeated that Moscow must withdraw its forces.
While they pounded away at the plant, Russian forces struggled to make significant gains elsewhere, 10 weeks into a devastating war that has killed thousands of people, forced millions to flee the country and flattened large swaths of cities.
The Ukrainian military's general staff said Friday that its forces repelled 11 attacks in the Donbas and destroyed tanks and armored vehicles, further frustrating Putin's ambitions after his abortive attempt to seize Kyiv. Russia gave no immediate acknowledgement of those losses.
The British Defense Ministry said Russia may be struggling to execute its plan in the Donbas partly because it's bogged down at the plant in Mariupol. The fighting at the plant "has come at personnel, equipment and munitions cost to Russia," it said. "Whilst Ukrainian resistance continues in Avozstal, Russian losses will continue to build and frustrate their operational plans in southern Donbas."
The Ukrainian army also said it made progress in the northeastern Kharkiv region, recapturing five villages and part of a sixth.